simple Hi-Tek coating

[HI-TEK]

Hi,
Thanks for the response. Please don't consider my probing as argumentative, just inquisitive because according to what you've stated above, I should be good. To your points:
1. The oven has an internal fan circulating the air, and the bullets are fully shielded from the elements by a tray of sand (I only use the bottom elements.)
2. Temperatures were taken from both a coated cast bullet with the TC inside the bullet, as well as a probe in the oven cavity itself at the level of the tray by different thermometers (calibrated within 5°F of each other.) In neither case, did the temperatures exceed 384°F (195.5°C.) Actually, the bullet temperature never quite got to the oven temperature. That's why I was leaning toward the duration of the cure more so than the temperature. I'll continue to try to perfect my technique and/or equipment to take full advantage of the Tru Blu. I know I'm getting very good, shootable bullets, so now it's all a matter of aesthetics!
Thank you again for your help.
Ed

Just a stupid question.
You mention using thermometers to measure temperatures.
Are you measuring oven air temperature or coated cast temperatures?
Air inside at a specific point in oven may be 195C, but that does not directly transfer as your load being at that same temperature.
Can you measure coated cast temperatures at given time intervals?
This will tell you a comparison between oven air temperature and product actual temperatures.

[RedlegEd]

Hi,
Thanks for the response. Please don't consider my probing as argumentative, just inquisitive because according to what you've stated above, I should be good. To your points:
1. The oven has an internal fan circulating the air, and the bullets are fully shielded from the elements by a tray of sand (I only use the bottom elements.)
2. Temperatures were taken from both a coated cast bullet with the TC inside the bullet, as well as a probe in the oven cavity itself at the level of the tray by different thermometers (calibrated within 5°F of each other.) In neither case, did the temperatures exceed 384°F (195.5°C.) Actually, the bullet temperature never quite got to the oven temperature. That's why I was leaning toward the duration of the cure more so than the temperature. I'll continue to try to perfect my technique and/or equipment to take full advantage of the Tru Blu. I know I'm getting very good, shootable bullets, so now it's all a matter of aesthetics!
Thank you again for your help.
Ed

Just a stupid question.
You mention using thermometers to measure temperatures.
Are you measuring oven air temperature or coated cast temperatures?
Air inside at a specific point in oven may be 195C, but that does not directly transfer as your load being at that same temperature.
Can you measure coated cast temperatures at given time intervals?
This will tell you a comparison between oven air temperature and product actual temperatures.

Hi.
Certainly not stupid questions, especially when you are trying to help. To your questions:

You mention using thermometers to measure temperatures. Yes, digital thermometers (see picture below,) as well as the PID therocouple that I use to control the oven. This probe is also at the same level of the bullet tray.

Are you measuring oven air temperature or coated cast temperatures? Both. As I stated in #2 of my post, "Temperatures were taken from both a coated cast bullet with the TC inside the bullet, as well as a probe in the oven cavity itself at the level of the tray by different thermometers (calibrated within 5°F of each other.)" The probe from the Dot is actually in the tray with the bullets.

Can you measure coated cast temperatures at given time intervals? Yes, I'll be happy to chart the temperatures with a tray load of bullets. It may take me a little bit before I can get to it, but I can do a simple test how long it takes the heat transfer of ambient to cast temperature at 190°C.

Ed

[RedlegEd]

I saw your initial photos taken inside. They seem to have a strange colour.
When you took it out into sunlight, they glowed Blue and lost that strange colour aspect.
The colours I see posted, seem also to be taken under indoor lighting and look very similar to first indoor photos.
If they are photographed indoors, I wonder how the posted Blue looks outside in full sun.

Hi.
I'm waiting for the sun to come out and I'll get a photo of the bullets in the sunlight. This is a bowl of my bullets taken under a white LED shop light.
Ed

[RedlegEd]

I saw your initial photos taken inside. They seem to have a strange colour.
When you took it out into sunlight, they glowed Blue and lost that strange colour aspect.
The colours I see posted, seem also to be taken under indoor lighting and look very similar to first indoor photos.
If they are photographed indoors, I wonder how the posted Blue looks outside in full sun.

Hi.
I'm waiting for the sun to come out and I'll get a photo of the bullets in the sunlight. This is a bowl of my bullets taken under a white LED shop light.
Ed

Hi,
Okay, sun came out and I took a pic in the sunlight. Still green/blue, not the deep midnight blue as Ausglock's samples.) BTW, I checked the picture I provided in an earlier post, that too was taken outside in the sun.
Ed

[lablover]

Do you guys do a smash test and acetone test after every coat? I have been but feel like I don’t need to...may have read that someplace.....

I’m getting good at this coating stuff... lol

Also, would I notice any accuracy differences with a batch coated twice and another coated 3 times? The 3 coats was done in my initial coatings try’s and now finding I’ve got it down pretty good that 2 coats is all I need. Pardini .32 target pistol

[RydForLyf]

Do you guys do a smash test and acetone test after every coat? I have been but feel like I don’t need to...may have read that someplace.....

I’m getting good at this coating stuff... lol

Not since getting comfortable with color and bake.

[Ausglock]

I only wipe smash about every 5000 or so.
I found no difference in accuracy or barrel cleanliness with 2 or 3 coats. 3 coats is a waste of coating and time for handgun bullets.

[Tazza]

I did it to start with, but don't check any more. You kinda get used to the smell when baking to know they hit the right temperature. Different colours i had to check just to be sure, but once i have my times, temperatures and qty of projectiles i put in the oven, it's the same every time, so no need to do the tests.

I do 3 coats just for looks, if i had no lube groove moulds, they would look awesome after 2 coats, just like Ausglock.

[lablover]

Thanks gents. I also did 3 coats just for looks but moving forward 2 coats is gonna be the ticket

[lablover]

Question. I assume the best time to coat is right after casting...I’ve done this and it works great as the bullets are clean. I have been sizing then I Swage my bullets after coating and am having some coating flake off all the sharps corners on the bullet. This only happens when I Swage the bullets. It’s fine if I just size. All my bullets pass the wipe and smash test. I’m wondering if the Swage process adds a bit too much stress to the coating?

I could Swage before coating but fear I’ll add some type of contamination to the raw bullet

Should I just shoot em and not worry about it?

I use aqua lube to size and Swage. It’s Hitek a brand lube

[kevin c]

I believe Joe himself has advised against sizing before coating because the sized surface doesn't bind the coating as well. I'd guess that'd apply to swaging too.

I've seen a very slight loss of coating on well cured boolits that I've pulled after loading for various reasons. I assume it has happened on other rounds I've loaded and shot, but haven't seen any leading in my polygonally rifled barrels. My guess is that so long as there's a good fit to the bore, adequate alloy hardness, and reasonable velocities, so long as most of the bearing surface is coated properly, I'm OK. YMMV.

[Ausglock]

You can do 1 coat, size, and then do another coat.
This allows the first coat to bond to the lead.
after that the second coat bonds to the first.
Not sure about swaging.
What is the start dia and the final dia?

Also...did a test on the weekend.
All my test coating is done with MEK, not Acetone.
So, I made a mix of TRUBLU with acetone to see if there was any difference in colour.
End result was exactly the same as with MEK.
The TRUBLU colour was identical.
this rules out any issues with using MEK or acetone.
The acetone was a shorter swirl time (15 seconds) MEK swirl time is around 25 seconds.

[lablover]

You can do 1 coat, size, and them do another coat.
This allows the first coat to bond to the lead.
after that the second coat bonds to the first.
Not sure about swaging.
What is the start dia and the final dia?

Also...did a test on the weekend.
All my test coating is done with MEK, not Acetone.
So, I made a mix of TRUBLU with acetone to see if there was any difference in colour.
End result was exactly the same as with MEK.
The TRUBLU colour was identical.
this rules out any issues with using MEK or acetone.
The acetone was a shorter swirl time (15 seconds) MEK swirl time is around 25 seconds.

I’ll give that a try. They fall out of the mold at .314 I size to .312 then Swage back up to .314. Kind of a klunky process but until I get a mold that will drop them out smaller than the Swage press needs I’m stuck with this process.

[Ausglock]

Thumping them back up 2 thou to .314 should not cause the coating to come off.

[flybyjohn]

Haven't coated for quite some time but just ran out of bullets so have to cast and coat again. I want to upgrade my oven. It is a black and decker 120v 1500 watt convection toaster oven. When I first started coating with hitek, I took apart the oven and wired it up to be controlled by a PID and wired the convection fan separate so it can run full time. I thought I had it working ok but trying to get consistency between the loads is not so good. The oven has a bulged out part in the back that has nice radius edges on the back wall, I think it was so you could get a pizza in it. Anyway, my idea is to put in a better convection fan in the center back of the oven with a plate in front of it that will be about 2/3 to 3/4 of the area of the back wall. The fan would suck air in through a hole in the center of the plate and blow it out radially, the air would circulate around the top, sides, and bottom walls of the oven (blowing over the 2 heating elements on the tops and bottom and then returning to the center to get sucked back in to the fan again. Not sure how many dead spaces there would be with this setup but willing to give it a try.

Now for the important question. The oven was built with so many dead air spaces on the sides and top and vents to let the air out all around it. I want to create a better, more constant temperature so that there is less of a temperature swing when loading and unloading bullets. I have heard that more permanent mass in the oven will help with this and if I insulate the air space between the inside oven wall and outside wall, it should be able to keep the mass i add inside the oven more constant. I have some ceramic fiber blanket insulation that I can use between the walls of the oven but I am not sure the best option of material to use for the inside mass of the oven.

Things available to me are ceramic tile, steel plate (rather not since its so heavy), or I can make some custom sized clay tiles and fire them at the local pottery place (I am a member). I have some leftover granite tiles also. what would be the best medium?

Now if this all doesn't sound like it is going to work, I have two boxes of used insulated fire brick that I was planing on making a heat treat oven with. I think I have enough for two ovens. the only problem with the fire brick is that with a high speed convection fan, it might blow a lot of dust around ( the kind you don't want to breath).

So what are your guys thoughts on making a good efficient Hitek oven for the occasional 2 - 3 times a year caster. Just to put it out there, I dont' have the room for a full size oven so that would not be an option, I do however have a 230 volt 30 amp outlet available that I use for my welder and lead pot.

Thanks for any suggestions you all might have.

[Ausglock]

The small convection benchtop oven can be improved.
1. Tear it down
2. Seal all the gaps of the oven compartment with silicone sealant.
3. Remove the convection fan and put more pitch on the fan blades. this improves air flow.
4. Place a clay paver block on the bottom of the oven.
5. Insulate the exterior of the oven compartment with rockwool or similar.
6. install PID control (you already have this).
Don't use the timer on the oven. get a digi timer (or stopwatch) from ebay etc.
I built one with a flasher/buzzer that alerts me when time is up. it is really annoying if you don't press the reset button...lol

Edit:
These small oven can have issues with wire connectors burning off where one heat element links to the next. this will cause heating failure.
When the oven is heating up, I visually check that all top and bottom elements are glowing red before baking anything. I have had to replace connectors a few times over the years.

[flybyjohn]

Thanks Ausglock. I’ll make those upgrades and see how it does.

[flybyjohn]

I bent the fan blades with more pitch and still did not have as much airflow as I was hoping for. So I went ahead and took the motor off made another fan blade from an old license plate that is half an inch larger in diameter and mounted the motor in the center of the back of the oven. I took the bottom crumb tray out of the oven and cut a plate with a hole in the center to go in front of the fan and direct the air coming out of the fan along the sides, top, and bottom of the oven. If I need more airflow I might need to get a bigger fan as this one is a very low amperage motor. All I have left to do is to make a silicone seal around the door glass. And possibly insulate the glass itself as it seemed to heat up very quickly when I tested it. The oven heats up a lot quicker now than it did before and I believe that after it is fully preheated the granite tile in the bottom should keep it at a steady temperature. I was quite surprised that the paper pattern on the fan blade did not come unglued on the first pre-heat cycle. That 3m spray adhesive is something else.

http://i.imgur.com/GbJshTD.jpg
http://i.imgur.com/W3p1sHJ.jpg
http://i.imgur.com/VaZTbNP.jpg

[Stephen Cohen]

I'm wondering at what point does a fan become to big or circulate too much air, am I right to think that the job of the fan is just to circulate hot air around the bullets and not turn oven into pressure vessal. Most bench top ovens mine included have vents for hot air to escape, I assume that is for air around the oven internals to escape, just wondering if bigger fan has a down side. Electronics is not my strong point but since I want a new oven I may try the mods Ausglock recommends and find out how much improvement I get, even though I am happy with what I have, a little more can't hurt. Regards Stephen

[flybyjohn]

My thought is that as long as the hot air can’t escape, it would be hard to give it too much air and as long as the air is just being recirculated and no new air is added, it just makes the air around the bullets more uniform and heats the coating faster.

Now I don’t know enough about thermodynamics or oven design to steer anybody in the direction I headed but it just seamed to make sense to me.